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The dry future of the Colorado River

A new study finds that even with very modest precipitation changes, water supplies in the upper Colorado River basin could significantly decline by 2100, with severe consequences for agriculture, urban supplies, and ecosystem health.

The Colorado River is widely considered the most important source of water in the western United States, providing water to 30 million people and large agricultural regions and generating 8 billion kilowatt hours of hydroelectric power annually.

Many previous studies have debated whether climate change will bring a wetter or drier future to the Colorado. In this paper, Researchers Darren Ficklin (now Indiana University), Iris Stewart (ESS) and Ed Maurer (CE) used the projections from established global climate models as input to a hydrologic model to forecast what is likely to happen to water flow and other hydrologic measures, such as evaporation and transpiration on a fine scale. Their findings show that the effects of highly likely warmer temperatures will be more important than either modest precipitation increases or decreases. Thus, even if the Colorado Basin will receive some more rain and snow in the future, warmer temperatures are forecast to lead to overall less water availability due to higher evaporation rates and a lot less snow that is melting earlier in the year. In addition, the higher evaporation could mean that soils in the basin will be dryer on average, such that the lower regions of the basin turn from semi-arid to arid conditions by the end of the century.

The full paper can be found at: Ficklin DL, Stewart IT, Maurer EP (2013) Climate Change Impacts on Streamflow and Subbasin-Scale Hydrology in the Upper Colorado River Basin. PLoS ONE 8(8): e71297. doi:10.1371/journal.pone.0071297

Funding for this work was provided by the US EPA under a STAR (Science to Achieve Results) Grant.